public async Task ReadWriteTransaction_QueryAbortsHalfway_WithDifferentUnseenResults_CanBeRetried(bool enableInternalRetries)
{
string sql = $"SELECT Id FROM Foo WHERE Id IN ({_fixture.RandomLong()}, {_fixture.RandomLong()})";
// Create a result set with 2 rows.
_fixture.SpannerMock.AddOrUpdateStatementResult(sql, StatementResult.CreateSingleColumnResultSet(new V1.Type {
Code = V1.TypeCode.Int64
}, "Id", 1, 2));
// The following will cause the ExecuteStreamingSql method on the mock server to return an Aborted error on stream index 1 (i.e. before the row with value 2 is returned).
// This simulates a transaction that is aborted while a streaming result set is still being returned to the client.
var streamWritePermissions = new BlockingCollection <int>
{
1
};
var executionTime = ExecutionTime.StreamException(MockSpannerService.CreateAbortedException(sql), 1, streamWritePermissions);
_fixture.SpannerMock.AddOrUpdateExecutionTime(nameof(MockSpannerService.ExecuteStreamingSql), executionTime);
using var connection = CreateConnection();
await connection.OpenAsync();
using var transaction = await connection.BeginTransactionAsync();
transaction.EnableInternalRetries = enableInternalRetries;
var cmd = connection.CreateSelectCommand(sql);
cmd.Transaction = transaction;
using var reader = await cmd.ExecuteReaderAsync();
// Only the first row of the reader.
Assert.True(await reader.ReadAsync());
Assert.Equal(1, reader.GetInt64(reader.GetOrdinal("Id")));
// Now change the result of the query, but only for the second row which has not yet been
// seen by this transaction.
_fixture.SpannerMock.AddOrUpdateStatementResult(sql, StatementResult.CreateSingleColumnResultSet(new V1.Type {
Code = V1.TypeCode.Int64
}, "Id", 1, 3));
// Try to get the second row of the result. This should succeed, even though the transaction
// was aborted, retried and the reader was re-initialized under the hood. The retry succeeds
// because only data that had not yet been seen by this transaction was changed.
executionTime.AlwaysAllowWrite();
if (enableInternalRetries)
{
Assert.True(await reader.ReadAsync());
Assert.Equal(3, reader.GetInt64(reader.GetOrdinal("Id")));
// Ensure that there are no more rows in the results.
Assert.False(await reader.ReadAsync());
// Check that the transaction really retried.
Assert.Equal(1, transaction.RetryCount);
}
else
{
var e = await Assert.ThrowsAsync <SpannerException>(() => reader.ReadAsync());
Assert.Equal(ErrorCode.Aborted, e.ErrorCode);
}
}
public SpannerMockServerFixture()
{
SpannerMock = new MockSpannerService();
_server = new Server
{
Services = { Google.Cloud.Spanner.V1.Spanner.BindService(SpannerMock) },
Ports = { new ServerPort("localhost", 0, ServerCredentials.Insecure) }
};
_server.Start();
}
public async Task ReadWriteTransaction_QueryAbortsHalfway_WithDifferentResults_FailsRetry()
{
string sql = $"SELECT Id FROM Foo WHERE Id IN ({_fixture.RandomLong()}, {_fixture.RandomLong()})";
// Create a result set with 2 rows.
_fixture.SpannerMock.AddOrUpdateStatementResult(sql, StatementResult.CreateSingleColumnResultSet(new V1.Type {
Code = V1.TypeCode.Int64
}, "Id", 1, 2));
// The following will cause the ExecuteStreamingSql method on the mock server to return an Aborted error on stream index 1 (i.e. before the row with value 2 is returned).
// This simulates a transaction that is aborted while a streaming result set is still being returned to the client.
var streamWritePermissions = new BlockingCollection <int>
{
1
};
var executionTime = ExecutionTime.StreamException(MockSpannerService.CreateAbortedException(sql), 1, streamWritePermissions);
_fixture.SpannerMock.AddOrUpdateExecutionTime(nameof(MockSpannerService.ExecuteStreamingSql), executionTime);
using var connection = CreateConnection();
await connection.OpenAsync();
using var transaction = await connection.BeginTransactionAsync();
var cmd = connection.CreateSelectCommand(sql);
cmd.Transaction = transaction;
using var reader = await cmd.ExecuteReaderAsync();
// Only the first row of the reader.
Assert.True(await reader.ReadAsync());
Assert.Equal(1, reader.GetInt64(reader.GetOrdinal("Id")));
// Now change the result of the query for the record that has already been seen.
_fixture.SpannerMock.AddOrUpdateStatementResult(sql, StatementResult.CreateSingleColumnResultSet(new V1.Type {
Code = V1.TypeCode.Int64
}, "Id", 3, 2));
executionTime.AlwaysAllowWrite();
// Try to get the second row of the result. This will now fail.
await Assert.ThrowsAsync <SpannerAbortedDueToConcurrentModificationException>(() => reader.ReadAsync());
Assert.Equal(1, transaction.RetryCount);
}
